City officials said that enhanced enforcement of illegal right turns on red is partially responsible for the spike.

The city has switched the red light cameras at 34 intersections from still photos to video. John Rago, deputy chief of staff to Mayor James Baker, says that's allowed police to more accurately detect drivers who don't come to a full stop before turning right.

He adds that if there's any doubt about whether a violation occurred, police won't issue a citation.

Officials say the cameras have cut the number of crashes by an average of 41 percent at their newest placements.